Basic HTML version of Foils prepared 7 October 97

Foil 34 Data Integrity in Oracle -II

From Untitled presentation ARL Database Tutorial -- February 98. by Gang Cheng, C.W. Ou, Geoffrey C. Fox
1 Integrity Constraints - a declarative way to define a business rule for a column of a table.
  • They are defined with a table and are stored as part of the table's definition
2 Following integrity constraints are supported by Oracle:
  • NOT NULL - disallow nulls (empty entries) in a table's column
  • UNIQUE - disallow duplicate values in a column or set of columns
  • PRIMARY KEY - disallow duplicate values and nulls in a column or set of columns
  • FOREIGN KEY - requires each value in a column or set of columns match a value in a related table's UNIQUE or PRIMARY KEY (FOREIGN KEY integrity constraints also define referential integrity actions that dictate what Oracle should do with dependent data if the data it references is altered)
  • CHECK - disallows values that do not satisfy the logical expression of the constraint
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